Piggyback Loan vs PMI

Overview

How to use this calculator

1. Enter the home price and your planned down payment percentage.
2. Enter the first mortgage rate (APR), second mortgage rate (APR), second mortgage percentage, PMI rate, and loan term in years.
3. Enter how many years you expect to keep the initial structure before refinancing, selling, or making major changes—the comparison period.
4. Review the PMI scenario outputs: single loan amount, approximate monthly PMI cost, and total monthly payment (P&I + PMI).
5. Review the piggyback scenario outputs: first mortgage payment, second mortgage payment, and combined monthly total.
6. Check the total amounts paid over the comparison period and the Savings over comparison period output to see which structure costs less over your chosen timeframe.

Inputs explained

Home price

The purchase price of the property. Together with your down payment percentage, this determines how much you borrow under both the PMI and piggyback structures.

Down payment (%)

The percentage of the home price you plan to pay in cash at closing. A 10% down payment on a $500,000 home means you put in $50,000 and finance the remaining 90%.

First mortgage rate (APR %)

The annual percentage rate for the primary (first lien) mortgage in both scenarios. Piggyback structures are often designed to keep this first mortgage at or below 80% loan-to-value to avoid PMI.

Second mortgage rate (APR %)

The annual percentage rate for the piggyback (second lien) mortgage, which usually carries a higher rate due to its junior position and risk profile.

Second mortgage percent (%)

The portion of the home price financed by the second mortgage in the piggyback scenario. For an 80/10/10 structure, enter 10. The first mortgage then covers roughly 80%, with your down payment covering the rest.

PMI rate (annual % of loan)

The annual cost of PMI as a percentage of the loan amount for the single-loan scenario. For example, a 0.5% PMI rate on a $450,000 loan implies $2,250 per year in PMI, or about $187.50 per month, before considering PMI drop-off.

Term (years)

The length of both mortgages in years (commonly 30 or 15). The calculator uses this to compute principal-and-interest payments under both structures.

Years to compare

How many years you want to analyze—typically how long you expect to keep the loan setup before refinancing or moving. The calculator multiplies monthly payments by this number of years to compare total dollars paid.

Outputs explained

Single loan amount with PMI

The principal balance of the single mortgage in the PMI scenario, equal to home price minus your down payment. This loan carries PMI until you build sufficient equity based on lender rules.

PMI monthly

The estimated monthly PMI charge on the single-loan structure, calculated from the PMI rate and loan amount. In reality, PMI may change or drop off as LTV improves; this model keeps it constant for your comparison window.

Payment with PMI (P&I + PMI)

The combined monthly payment for principal and interest on the single mortgage plus the estimated monthly PMI cost, excluding taxes, insurance, and HOA dues.

First mortgage (piggyback)

The monthly principal-and-interest payment on the first mortgage in the piggyback structure, sized to keep the first loan at or below your target LTV threshold (often 80%).

Second mortgage (piggyback)

The monthly principal-and-interest payment on the second (piggyback) mortgage, based on the second mortgage percentage and second mortgage rate you entered.

Piggyback monthly total

The sum of first and second mortgage payments in the piggyback structure, representing your total monthly P&I payment before taxes and insurance.

Savings over comparison period

The difference between total payments in the PMI scenario and the piggyback scenario over the comparison period. A positive value indicates the piggyback structure costs less; a negative value indicates PMI is cheaper over that window.

Months in comparison

The total number of months in your comparison period (Years to compare × 12). This is used to scale monthly payments for total cost comparisons.

When to use it

• Evaluating whether an 80/10/10 or 80/15/5 piggyback structure reduces your monthly payment or total near‑term cost compared with a single mortgage plus PMI.
• Checking how sensitive the comparison is to second-mortgage rates—since seconds often have higher rates, small changes can swing the math.
• Modeling your expected time in the loan before refinancing to see whether a short-term piggyback advantage outweighs long-term simplicity of a single loan with PMI that eventually drops off.
• Using the results to have more informed conversations with lenders about down payment strategies, concessions, and product options.
• Helping you decide where to deploy limited cash—toward a higher down payment to avoid PMI, or to cover closing costs while accepting PMI.

Tips & cautions

• Be realistic about your time horizon. If you expect to refinance or move within a few years, focus your comparison period on that timeframe to see which option is more cost-effective in the short run.
• Second mortgages may have different terms, prepayment penalties, or balloon features—always review the specific loan terms, not just the rate.
• Remember that PMI can sometimes be removed when your equity reaches certain thresholds and conditions are met. You can approximate this by shortening the comparison period for the PMI scenario or by modeling a lower PMI rate over time in more detailed tools.
• Consider the psychological and administrative simplicity of having one loan versus two; even if payments are similar, some borrowers prefer fewer moving parts.
• Run multiple what‑if scenarios with different PMI rates, second‑mortgage rates, and down payment percentages to understand how sensitive the comparison is to your assumptions.
• Uses a simplified PMI model that applies a constant PMI charge during the comparison window; actual PMI often changes with LTV and may terminate earlier than modeled.
• Assumes fixed rates and equal terms for both first and second mortgages; variable‑rate seconds or different amortization schedules are not modeled.
• Excludes taxes, insurance, HOA dues, closing costs, points, lender credits, and other transaction costs that can materially affect the overall economics of each option.
• Does not enforce program-specific rules about maximum second‑mortgage percentages, DTI requirements, or credit score thresholds for piggyback loans.
• Provides a payment-focused comparison only and should be supplemented with a full review of fees, risk, and long-term plans before deciding.

Deep dive

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